Stuck on Repeat, repeat, repeat...

I am a scratched record, or a song stuck on repeat. Why am I so surprised when he is rude and cold? I knew he was mentally ill. I thought it was treatable...and maybe it is...for someone that wants to feel better. I am reminded of the song by Papa Roach "Scars". It doesn't matter how many times I offer my hand while he is drowning...he pushes it away. I have opened my heart and handed it to him...everytime he asked. The first time I didn't know not to. Every time after that I did it, because he apologized and said he would do better. Now...I struggle, because I know he will take the mashed, shredded, mangled tidbits of my heart that are left and systematically destroy it. How did I get here? What if it is a traumatic brain injury? What if this was all caused by his mother beating him as a child? What if it was compounded by being crushed under a car as a young boy? What if it has been further damaged by sports trauma as a teen, and now through a concussion from another MVA? It feels like he can control his behavior when he wants to...so why doesn't he want to control it enough not to harm me? How do people stay married for 50 years to people that are not whole? If they are whole...where the hell are those people??